Electrode beam welded spark plugs for industrial electrodes

Abstract

An industrial spark plug (20) includes a central electrode (24) with a central base (30) formed of a nickel-based material and a central firing tip (32) formed of an iridium-based material. The central firing tip (32) has a tip thickness (tct) of 0.02 to 0.03 inches, a tip diameter (dct) of 0.1184 to 0.1776 inches, and an aspect ratio of 4.736 to 7.104. The central firing tip (32) is electron beam welded to the central base (30) to provide a robust joint therebetween. The central electron beam weld (36) includes a mixture of re-crystallized iridium-based material and re-crystallized nickel-based material extending continuously along and over the entire welding interface. The spark plug (20) also includes a ground electrode (26) with a ground firing tip (38) electron beam welded to a ground base (42).

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates generally to spark plugs for internal combustion engines, and more particularly to electrode firing tips of the spark plugs and methods of forming the same.[0003]2. Description of the Prior Art[0004]Spark plugs of internal combustion engines for automotive and industrial applications typically include a central electrode and a ground electrode providing a spark gap therebetween. The electrodes provide a spark to ignite a mixture of fuel and air in a combustion chamber of an internal combustion engine. The electrodes, especially the firing ends along the spark gap, are exposed to high temperatures and extreme conditions in the combustion chamber. Thus, the electrodes are oftentimes designed to include a firing tip formed of precious metal material welded to a based formed of a nickel material. An example of this type of electrode is disclosed in U.S. Pat. No. 7,948,159 to Lykowski. The firing tip d...

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